This study comprehensively investigated the occurrence, sources, and potential toxicity risks of 16 PAHs in main urban area surface soils of Changchun, northeast China. The 16 total PAHs (Σ 16 PAHs) concentrations in surface soils decreased significantly along the commercial traffic district, industrial zone, residential zone, park zone, and outskirt farmland, ranging from 46.6 to 8870.8 ng/g, with a mean value of 1480.1ng/g and 4-ring PAHs were always the dominant constituents in all land used area soils. Based on ArcGIS mapping, higher concentrations of PAHs are mainly concentrated in the northeast region and the central historic district soils of Changchun city. Mixed pyrogenic sources and coal combustion were the dominant sources and contributed approximately 45% and 30% of the total soil PAHs, respectively. Toxicity risk assessment based on the toxic equivalent concentrations (BaP eq ) of soil PAHs indicated the potential toxicity risks detected in this study were relatively moderate compared with other global cities, while some special attention still should be paid to hotspots with high PAHs concentrations surrounding the commercial traffic area and industrial zone in the northeast pattern of Changchun city. This study could be potentially useful for local governments targeted to control toxicity exposure, promote actions to alleviate PAHs contamination.

Portable X-ray fluorescence spectrometry (pXRF) is an analytical technique that can be used for rapid and non-destructive analysis in the field. However, the testing accuracy and precision for trace elements are significantly affected by the matrix effect, which comes mainly from major elements that constitute most of the matrix of a sample. To solve this problem, many methods based on linear regression models have been proposed, but when extreme values or outliers occur, the application of these methods will be greatly affected. In this study, 16 certified reference materials were collected for pXRF analysis, and the major elements most closely related to the elements to be measured were employed as correction indicators to calibrate the analysis results through the application of multiple linear regression analysis. Some statistical parameters were calculated to evaluate the correction results. Compared with the calibration data obtained from simple linear regression analysis without taking major elements into account, those corrected by the new method were of higher quality, especially for elements of Co, Zn, Mo, Ta, Tl, Pb, Cd and Sn. The results show that the new method can effectively suppress the influence of the matrix effect.

48 surface soil samples from the main urban areas in Changchun, Northeast China were analyzed for 18 organochlorine pesticides (OCPs) with the aim of elucidating their contamination status, distribution characteristics, influencing factors, and potential risks in this urban region. The total concentrations of OCPs ranged from 15.63 to 92.79 ng/g, with the geomean of 36.46ng/g. HCHs, DDTs, and Chlordanes were the most dominant OCPs, with γ-HCH and p,p'-DDT being the predominant isomer. Higher concentrations of OCPs mainly concentrated in the northeast and southwest of Changchun city and the artificial influences contributed to the fate of OCPs in the soils. The residues of OCPs were mainly derived from the historical application of the technology DDT, dicofol, and lindane. Pearson’s correlation analysis indicated that TOC was a key factor controlling OCPs accumulation. The data analysis based on the soil quality guidelines (SQGs) suggested that the presence of DDTs, lindane, and heptachlor may pose a certainly toxic ecological threat to the soil organisms. The evaluation results of incremental lifetime cancer risk (ILCR) showed that the cancer risk of OCPs to the posed population was low, while some specific locations with high OCPs residues ought to be a cause for concern.

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